Lesson II-1- Theoretical contributions to the study of stress Flashcards
Summarize the theories of Walter Cannon and Hans Selye.
- Cannon coined the term “fight-or-flight response”, and proposed that when an organism perceives a threat, the body is rapidly aroused and motivated via the sympathetic nervous system and the endocrine system to carry out a fight-or-flight response. At one time, fight-or-flight literally referred to fighting or fleeing in response to stressful events such as attack by a predator. Now more commonly fight refers to aggressive responses to stress, whereas flight may be seen in social withdrawal or withdrawal through substance use such as alcohol or drugs.
- Hans Selye theorized that all stressors produce the same pattern of response, called the general adaptation syndrome, which consists of three phases: In the first phase, which he called alarm, the organism becomes mobilized to meet the threat. In the second phase, resistance, the organism makes efforts to cope with the threat, as through confrontation. The third phase, exhaustion, occurs if the organism fails to overcome the threat and depletes its physiological resources in the process of trying.
List three criticisms of the general adaptation syndrome.
- It assigns a very limited role to psychological factors, and researchers now believe that the psychological appraisal of events is important in the determination of stress.
- The theory assumes that responses to stress are uniform, but not all stressors produce the same endocrinological responses. How people respond to stress is substantially influenced by their personalities, perceptions and biological constitutes.
- It treats stress as an outcome, which is evident only when the general adaptation syndrome has run its course, rather than as a process.
Describe Taylor’s tend-and-befriend theory.
The theory maintains that in addition to fight-or-flight, humans can respond to stress with social affiliation and nurturant behavior toward offspring.
Distinguish among harm, threat and challenge.
- Harm is the assessment of the damage that has already been done by an event. Thus, for example, a man who has just been fired from his job may perceive present harm in terms of his own loss of self-esteem and his embarrassment as his coworkers silently watch him pack up his desk.
- Threat is the assessment of possible future damage that may be brought about by the event. Thus, the man who has just lost his job may anticipate problems that the loss of income will create for him and his family in the future. Primary appraisals of events as threats have important effects on physiological responses to stress. For example, blood pressure is higher when threat is higher or when threat is high and challenge is low.
- Challenge is the potential to overcome and even profit from an event. For example, the man who has lost his job may perceive that a certain amount of harm and threat exists, but he may also see his unemployment as an opportunity to try something new. Challenge appraisals are associated with more confident expectations of the ability to cope with the stressful event, more favorable emotional reactions to the event, and lower blood pressure.
Summarize the findings of Speisman et al (1964).
College students viewed a gruesome film depicting unpleasant tribal initiation rites that included genital surgery. Before viewing the film, they were exposed to one of four experimental conditions. One group listened to an anthropological account about the meaning of the rites. Another group heard a lecture that deemphasized the pain the initiates were experiencing and emphasized their excitement over the events. A third group heard a description that emphasized the pain and trauma that the initiates were undergoing. A fourth group was given no introductory information, and the film they viewed had no sound track.
Measures of autonomic arousal (skin conductance, heart rate) and self-reports suggested that the first two groups experienced considerably less stress than did the group whose attention was focused on the trauma and pain. Thus, not only was intrinsic to the gruesome film itself but also depended on the viewer’s appraisal of it.
Discuss the role of the SAM system and the HPA axis in stress response.
- The sympathetic-adrenomedullary (SAM) system produces epinephrine and norepinephrine in response to stress. When events are encountered that are perceived as harmful or threatening, they are labeled as such by the cerebral cortex, which, in turn sets off a chain of reactions mediated by these appraisals. Information from the cortex is transmitted to the hypothalamus, which initiates one of the earliest responses to stress – namely, sympathetic nervous system arousal, or the fight-or-flight response. Sympathetic arousal stimulates the medulla of the adrenal glands, which, in turn, secret the catecholamines epinephrine, and norepinephrine. These effects result in the cranked-up feeling we usually experience in response to stress.
- In addition to the activation of the sympathetic nervous system, the hypothalamic-adrenal pituitary (HPA) axis is activated in response to stress. The hypothalamus releases corticotrophin-releasing factor (CRF), which stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH), which, in turn, stimulates the adrenal cortex to release glucocorticoids. Of these, cortisol is especially significant. It acts to conserve stores of carbohydrates and helps reduce inflammation in the case of an injury. It also helps the body return to its steady state following stress. HPA activation also produces elevations in growth hormone and prolactin, secreted by the pituitary gland.
Describe the long-term effects of stress on the body.
-Over the long term, excessive discharge of epinephrine and norepinephrine can lead to suppression of cellular immune function; produce hemodynamic changes, such as increased blood pressure and heart rate; provoke variations in normal heart rhythms, such as ventricular arrhythmias, which may be a precursor to sudden death; and produce neurochemical imbalances that may contribute to the development of psychiatric disorders. The catecholamines may also have effects on lipid levels and free fatty acids, all of which may be important in the development of atherosclerosis.
-Prolonged cortisol secretion has also been related to the destruction of neurons in the hippocampus. This destruction can lead to problems in verbal functioning, memory, and concentration, and may be one of the mechanisms leading to senility.
Pronounced HPA activation is common in depression, with episodes of cortisol secretion being more frequent and of longer duration among depressed than non-depressed people, although it is not entirely clear whether HPA activation is a cause or an effect of these disorders.
-Another long-term consequence of the endocrine abnormalities that result from chronic HPA activation is the storage of fat in central visceral areas, rather than to the hips. This accumulation leads to a high waist-to-hip ratio, which is used by some researchers as a marker for chronic stress.
-Stress may also impair the immune system’s capacity to respond to hormonal signals that terminate inflammation.
-The combination of emotional arousal and neuroendocrine activation due to chronic stress may indeed underlie chronic insomnia. Because sleep represents a vital restorative activity, this mechanism, too, may represent an important pathway to disease.
Indicate how cardiovascular reactivity is related to stress.
Reactivity is, in part, a genetically-based predisposition to respond physiologically to environmental threats or challenges that may be implicated in both short and long-term health complications due to stress. Cardiovascular reactivity to stress can affect vulnerability to illness. For example, in one study, a group of children ranging in age from 3 to 5 years old were tested for their cardiovascular reactivity (change in heart rate and blood pressure) or their immune response to a vaccine challenge following a stressful task. The results indicated that stress was associated with increased rates of illness only among the children who had previously shown strong immune or cardiovascular reactions. The less reactive children did not experience any change in illness under stressful circumstances.
Identify the indicators used to assess allostatic load. (9)
- Decreases in cell-mediated immunity
- The inability to shut off cortisol in response to stress
- Lowered heart rate variability
- Elevated epinephrine levels
- A high waist-to-hip ratio (reflecting abdominal fat)
- Hippocampal volume (which is believed to decrease with repeated stimulation of the HPA)
- Problems with memory
- High plasma fibrinogen
- Elevated blood pressure
stress
Appraising events as harmful, threatening, or challenging and assessing one’s capacity to respond to those events; events that are perceived to tax or exceed one’s resources are seen as stressful.
stressors
Events perceived to be stressful.
fight or flight response
A response to threat in which the body is rapidly aroused and motivated via the sympathetic nervous system and the endocrine system to attack or flee a threatening stimuli; the response was first described by Walter Cannon in 1932.
general adaptation syndrome
Developed by Hans Selye, a profile how organisms respond to stress; the general adaptation syndrome is characterized by three phases: A nonspecific mobilization phase, which promotes sympathetic nervous system activity; a resistance phase, during which the organism makes efforts to cope with the threat; and an exhaustion phase, which occurs if the organism fails to overcome the threat and depletes its physiological resources.
primary appraisal
The perception of a new or changing environment as beneficial, neutral, or negative in its consequences; believed to be a first step in stress and coping.
secondary appraisal
The assessment of one’s coping abilities and resources and judgment as to whether they will be sufficient to meet harm, threat, or challenge of a new or changing event.
